I detta examensarbete har ett system för navigering och styrning av ett autonomt fordon implementerats. Syftet med detta arbete är att vidareutveckla fordonet som ska användas vid utvärdering av banplaneringsalgoritmer och studier av andra autonomifunktioner. Med hjälp av olika sensormodeller och sensorkonfigurationer går det även att utvärdera olika strategier för navigering. Arbetet har utförts utgående från en given plattform där fordonet endast använder sig av enkla ultraljudssensorer samt pulsgivare på hjulen för att mäta förflyttningar. Fordonet kan även autonomt navigera samt följa en enklare given bana i en känd omgivning. Systemet använder ett partikelfilter för att skatta fordonets tillstånd med hjälp av modeller för fordon och sensorer. Arbetet är en fortsättning på projektet Collision Avoidance för autonomt fordon som genomfördes vid Linköpings universitet våren 2005. / In this thesis a system for navigation and control of an autonomous ground vehicle has been implemented. The purpose of this thesis is to further develop the vehicle that is to be used in studies and evaluations of path planning algorithms as well as studies of other autonomy functions. With different sensor configurations and sensor models it is also possible to evaluate different strategies for navigation. The work has been performed using a given platform which measures the vehicle’s movement using only simple ultrasonic sensors and pulse encoders. The vehicle is able to navigate autonomously and follow a simple path in a known environment. The state estimation is performed using a particle filter. The work is a continuation of a previous project, Collision Avoidance för autonomt fordon, at Linköpings University in the spring of 2005.

Les travaux de recherche entrent dans le cadre de la reconfiguration de lois de commande des systèmes dynamiques présentant divers modes de fonctionnement afin d’assurer les performances désirées. Deux approches d’accommodation ont été proposées pour la commande de ces systèmes dynamiques : une approche passive qui présente un régulateur à paramètres fixes ne garantissant pas les mêmes performances pour différents modes de fonctionnement et une approche active dans laquelle les paramètres du système de commande peuvent être mis à jour selon le mode de fonctionnement détecté. C’est cette deuxième approche basée sur une représentation multi-modèles du système qui a été retenue dans nos travaux.Les erreurs de modélisation correspondant aux variations de conditions de fonctionnement, sont dans ce cas détectées par un algorithme de détection et de localisation de variations de modes de fonctionnement. Il s’en suit une reconfiguration d’une loi de commande par platitude en utilisant le principe de commutation. Cette approche garantit la régulation et la poursuite d’une trajectoire de référence. Pour sa mise en œuvre, un banc de régulateurs, conçu par platitude, a été élaboré pour les modèles discrets plats obtenus autour des divers points de fonctionnement.La détection des modes de fonctionnement est effectuée par une génération de résidus en utilisant un ensemble d’observateurs de type Luenberger dont les gains sont calculés en utilisant l’outil LMI.L'étude de la stabilité ainsi que l'introduction de dispositifs d'anti-emballement liés à la commutation entre les régulateurs, ont été considérés dans l'approche proposée / The work presented in this memory concerns the control reconfiguration of dynamical systems with variation of operating modes in order to ensure the desired performances. For the control of dynamic systems, two approaches of accommodation have been proposed. The passive approach presents a controller with fixed parameters that doesn’t ensure the same performance for different operating modes and an active approach in which the controller settings can be updated according to the variation of the detected operating mode. Our work has therefore focused on this second approach based on multi-models system representation. The modelling errors corresponding to the variations of operating conditions are detected in this case by detection and localization algorithm, consequently, a reconfiguration strategy based on flatness-based switching control is proposed. This approach guarantees the control and the tracking of a reference trajectory. In fact, we have synthesised a discrete flatness-based multi-controllers associated for each operating model obtained from different operating points. Detection of operating modes is done by a residual generation by using Luenberger observers which gains are calculated using the LMI tool. Study of the stability as well as the use of anti-windup devices related to switching between controllers; have been considered in the proposed approach

A mobile manipulator is a robotic arm mounted on a robotic mobile platform. In such a system, the degrees of freedom of the mobile platform are combined with that of the manipulator. As a result, the workspace of the manipulator is substantially extended. A mobile manipulator has two trajectories: the end-effector trajectory and the mobile platform trajectory. Typically, the mobile platform trajectory is not defined and is determined through inverse kinematics. But in some applications it is important to follow a specified mobile platform trajectory. The main focus of this work is to determine the inverse kinematics of a mobile manipulator to follow the specified end-effector and mobile platform trajectories, especially when both trajectories cannot be exactly followed simultaneously due to physical limitations. Two new control algorithms are developed to solve this problem. In the first control algorithm, three joint-dependent control variables (spherical coordinates D, α and β) are introduced to define the mobile platform trajectory in relation to the end-effector trajectory and vice versa. This allows direct control of the mobile platform motion relative to the end-effector. Singularity-robust and task-priority inverse kinematics with gradient projection method is used to find best possible least-square solutions for the dual-trajectory tracking while maximizing the whole system manipulability. MATLAB Simulated Planar Mobile Manipulation is used to test and optimize the proposed control system. The results demonstrate the effectiveness of the control system in following the two trajectories as much as possible while optimizing the whole system manipulability measure. The second new inverse kinematics algorithm is introduced when the mobile platform motion is restricted to stay on a specified virtual or physical track. The control scheme allows xii the mobile manipulator to follow the desired end-effector trajectory while keeping the mobile platform on a specified track. The mobile platform is moved along a track to position the arm at a pose that facilitates the end-effector task. The translation of the redundant mobile manipulator over the mobile platform track is determined by combining the mobility of the platform and the manipulation of the redundant arm in a single control system. The mobile platform is allowed to move forward and backward with different velocities along its track to enable the end-effector in following its trajectory. MATLAB simulated 5 DoF redundant planar mobile manipulator is used to implement and test the proposed control algorithm. The results demonstrate the effectiveness of the control system in adjusting the mobile platform translations along its track to allow the arm to follow its own trajectory with high manipulability. Both control algorithms are implemented on MATLAB simulated wheelchair mounted robotic arm system (WMRA-II). These control algorithms are also implemented on real the WMRA-II hardware. In order to facilitate mobile manipulation, a control motion scheme is proposed to detect and correct the mobile platform pose estimation error using computer vision algorithm. The Iterative Closest Point (ICP) algorithm is used to register two consecutive Microsoft Kinect camera views. Two local transformation matrices i. e., Encoder and ICP transformation matrices, are fused using Extended Kalman Filter (EKF) to filter the encoder pose estimation error. VICON motion analysis system is used to capture the ground truth of the mobile platform. Real time implementation results show significant improvement in platform pose estimation. A real time application involving obstacle avoidance is used to test the proposed updated motion control system.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第18406号 / 情博第521号 / 新制||情||92(附属図書館) / 31264 / 京都大学大学院情報学研究科数理工学専攻 / (主査)教授 太田 快人, 教授 梅野 健, 教授 大塚 敏之 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第21918号 / 情博第701号 / 新制||情||120(附属図書館) / 京都大学大学院情報学研究科システム科学専攻 / (主査)准教授 西原 修, 教授 大塚 敏之, 教授 加納 学 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Vertical Take-Off and Land (VTOL) Unmanned Air Vehicles (UAVs) possess several desirable characteristics, such as being able to hover and take-off or land in confined areas. One type of VTOL airframe, the tailsitter, has all of these advantages, as well as being able to fly in the more energy-efficient level flight mode. The tailsitter can track trajectories that successfully transition between hover and level flight modes. Three methods for performing transitions are described: a simple controller, a feedback linearization controller, and an adaptive controller. An autopilot navigational state machine with appropriate transitioning between level and hover waypoints is also presented. The simple controller is useful for performing a immediate transition. It is very quick to react and maintains altitude during the maneuver, but tracking is not performed in the lateral direction. The feedback linearization controller and adaptive controller both perform equally well at tracking transition trajectories in lateral and longitudinal directions, but the adaptive controller requires knowledge of far fewer parameters.

The Atomic Force Microscope (AFM) is a powerful tool for studying structure and dynamics at the nanometer scale. Despite its wide application in many applications, the slow imaging rate of AFM remains a severe limitation. Non-raster methods seek to overcome this limitation by appealing to alternative scan patterns, either designed to be easier for the actuators to follow or to reduce the amount of sampling needed. One particular example in this latter category is the local circular scan (LCS). LCS reduces the imaging time by scanning less sample area rather than scanning faster. It drives the tip of the AFM along a circular trajectory, using feedback to center that circle on a sample edge, and moving the circle along the feature, thus concentrating the samples to the region of interest. While this approach can have a significant impact on improving the imaging rate of any AFM, its impact is further enhanced when it is combined with high speed scanners. Due to its unique scanning pattern, a high-speed, Dual-Stage Actuator (DSA) system is a natural fit. DSAs consist of the serial combination of a (relatively) low-speed, long-range piezoelectric actuator (LRA) and a high-speed, short-range piezoelectric actuator (SRA). The SRA can be dedicated to implementing the local circular motion and the LRA to tracking the underlying sample. However, the control of a DSA scanner is challenging for at least three reasons: it is a multi-input, single-output system, it is a highly resonant system due to the underlying piezoelectric actuators, and it is a high-speed system. In this thesis, we address these challenges. First, we establish the controllability and observability of a general N-stage system whose outputs are summed to produce a single signal. This property allows us to develop individual controllers for the LRA and SRA of a DSA system so that we can focus our design on the specific requirements of each component and its desired action. While we apply both a Model Predictive Control (MPC) and simple state feedback approach to the LRA, our primary focus is on the SRA element as its high speed character makes it the more challenging component. Here we turn to receding horizon Linear Quadratic Tracking (LQT) control and develop methods to implement this approach at high speed using a Field Programmable Gate Array (FPGA). We develop three variants of LQT that differ in the required sample rates, memory resources, and computing power. Implementing and testing all three in both simulation and on a DSA scanning stage in our lab, we compare their performance and address the practical implementation considerations under the limitations imposed by the hardware. Finally, we combine the control of the LRA and SRA in two axes to demonstrate the LCS scanning approach. Overall, this thesis achieves a practical implementation of a model-based receding LQT design on a dual-stage, high speed, highly resonant actuator system. Through both simulation and experimental results, we demonstrate that this approach is robust to modeling error and disturbances and suitable for high-speed implementation of the LCS approach to non-raster AFM. / 2023-08-29T00:00:00Z

Many real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the chained systems while pursuing inverse optimality and exponential convergence rates, as well as the feed-back stabilization problem under input saturation constraints. These studies are based on global singularity-free state transformations and controls are synthesized from resulting linear systems. Then, the application of optimal motion planning and dynamic tracking control of nonholonomic autonomous underwater vehicles is considered. The obtained trajectories satisfy the boundary conditions and the vehicles' kinematic model, hence it is smooth and feasible. A collision avoidance criteria is set up to handle the dynamic environments. The resulting controls are in closed forms and suitable for real-time implementations. Further, dynamic tracking controls are developed through the Lyapunov second method and back-stepping technique based on a NPS AUV II model. In what follows, the application of cooperative surveillance and formation control of a group of nonholonomic robots is investigated. A designing scheme is proposed to achieves a rigid formation along a circular trajectory or any arbitrary trajectories. The controllers are decentralized and are able to avoid internal and external collisions. Computer simulations are provided to verify the effectiveness of these designs.

The Mechatronics group in the Mechanical Engineering department of Cal Poly is interested in creating a demonstration of a ball-and-plate trajectory tracking controller on hardware. The display piece will serve to inspire engineering students to pursue Mechatronics and control theory as an area of study. The ball-and-plate system is open-loop unstable, underactuated, and has complicated, nonlinear equations of motion. These features present substantial challenges for control - especially if the objective is trajectory tracking. Because the system is underactuated, common nonlinear trajectory tracking control techniques are ineffective. This thesis lays out a theoretical foundation for controlling the hardware. Several important concepts related to ball-and-plate trajectory tracking control are presented. Models of the system, with various assumptions, are given and used in deriving control law candidates. To limit project scope, reasonable control criteria are introduced and used to evaluate designs from the thesis. Several control architectures are explored, these being Full-State Feedback with Integral Action, Single-Input-Single-Output Sliding Mode, and Full-State Feedback with Feed Forward. The mathematical reasoning behind each is detailed, simulation results are shown to validate their practicality and demonstrate features of the architectures, and trajectory similarity measure studies are produced to evaluate controller performance for a wide range of setpoint functions. The Full-State Feedback with Feed Forward controller is recommended based on its theoretical advantages and compliance with the control criteria over the competing designs. The control architecture has a proof of asymptotic tracking in the linear model, has excellent performance in simulations that use a nonlinear plant model, and produces the most pleasing visual experience when viewed in animation.

Yes / This paper presents an iterative learning scheme for vision guided robot trajectory tracking. At first, a stability criterion for designing iterative learning controller is proposed. It can be used for a system with initial resetting error. By using the criterion, one can convert the design problem into finding a positive definite discrete matrix kernel and a more general form of learning control can be obtained. Then, a three-dimensional (3-D) trajectory tracking system with a single static camera to realize robot movement imitation is presented based on this criterion.